dart-use-pattern-matching

Use switch expressions or if-case statements with patterns like Map, List, Record, or Object patterns to match and destructure data. For example, `if (data case {'user': [String name, int age]})` validates JSON structure and binds variables in one step.

Use a switch expression when producing a value, since each case is a single expression with no fallthrough and must be exhaustive. Use a switch statement when executing side effects, where non-empty cases implicitly break and empty cases fall through.

Combine Map and List patterns to validate structure and extract values simultaneously. A pattern like `{'user': [String name, int age]}` checks the keys and types while binding name and age to local variables.

This error appears when switching over sealed classes or enums without covering all subtypes. Run dart analyze to find the missing cases, then add Object patterns for each unhandled subtype or a wildcard (_) case as a fallback.

Yes, relational patterns (>=, <=, ==) match against constant expressions, and guard clauses using `when` evaluate arbitrary conditions after a pattern matches. Logical-and (&&) and logical-or (||) patterns combine multiple matchers in one case.